[rules-users] Will the alternative lead to a better performance?

[Edson Tirelli]

   Stephen,

   As long as you use an "==" constraint as your example shows, the 
first alternative will be more performatic. This is because drools 
indexes facts based on your constraints. So, your first case will 
require a single "==" comparison to find user name "A" and a single 
comparison to find user name "B". Of course, if you have huge amound of 
objects where hashcode for name start to clash, you may have more than 
one comparison, but the effect is negligible when compared to all other 
costs of having that many facts.

   Second alternative works and will also hash object types, but it will 
create a lot more infrastructure classes and Rete Nodes to deal with 
your 500 different classes. So it is a worst alternative for the 
proposed scenario.

   []s
   Edson


Premkumar Stephen wrote:

> Hi,
>
> Consider that I have 500 instances of interface userI. Now, there are 
> 3000 rules currently written based on a combination of these instances.
>
> if {
>      $a : userI (name = "A")
>      $b : userI (name = "B")
> }
> then
> {
>  //do some actions
> }
>
> How many tests are needed for a match in the RETE network for this rule?
>
> If I created 500 classes, one for each object, such as UserA 
> implements userI and so on... my rule will look like:
>
> if {
>      $a : UserA()
>      $b : UserB()
> }
> then
> {
>  //do some actions
> }
>
> Will this lead to better performance since there will only be one such 
> instance of this object?
>
> As for class-loading concerns, will there be a parsing/memory penalty 
> to be paid for having 500 classes now instead of one?
>
> Thanks!
>
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-- 
 Edson Tirelli
 Software Engineer - JBoss Rules Core Developer
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